The standardization of new high-density optical disks capable of recording large amounts of high-quality video and audio data has been progressing rapidly and new optical disk related products are expected to be commercially available on the market in the near future. The Blu-ray Disc Rewritable (called ‘BD-RE’ in general) is one example of these new optical disks.
As shown in FIG. 1, a BD-RE disk comprises a clamping area, a transition, area, a burst cutting area (BCA), a lead-in area, a data area, and a lead-out area in order starting from the innermost circumference.
The lead-in area comprises several pre-assigned areas such as a first guard (Guard 1) area, a permanent information & control data (PIC) area, a second guard (Guard 2) area, a second information (Info 2) area, and an optimum power calibration (OPC) area. The Guard 1 area and the PIC area are pre-recorded areas in which some initial data is pre-recorded, whereas the other areas of the lead-in area, the data area, and the lead-out areas are all rewritable areas.
In the PIC area, important information about the disk, which is to be preserved permanently, is encoded in a wobbled groove by high frequency modulation (HFM). As shown in FIG. 2, the wobble-shaped data encoding is performed by bi-phase modulation.
In the mean time, the development of the read-only Blu-ray disk (BD-ROM) is also under way along with the development of the BD-RE. A BD-ROM disk comprises an inner area, a clamping area, a transition area, an information area, and a rim area, as shown in FIG. 3.
The contents of A/V streams are recorded in the data zone belonging to the information area in an encrypted manner using the copy protection information (CPI) with a view to preventing an illegal copying of the contents.
Disc information (DI) such as disc type is recorded in the PIC area belonging to the information area. In the case where the main data recorded in the data zone is encrypted, copy protection information (CPI) for decrypting the encrypted data is also recorded in the PIC area.
When an optical disk (a BD-ROM disk) is loaded into an optical disk reproducing apparatus, the optical disk reproducing apparatus first detects the copy protection information (CPI) recorded in the PIC area and then decrypts the main data recorded in the data zone using the copy protection information (CPI) if the main data is encrypted.
If an error occurs when the apparatus detects the copy protection information (CPI), which is required to decrypt the encrypted data, the contents of the BD-ROM disk cannot be decoded even if there in no data read error.